kernel ISI trap on macppc after recent changes

["John D. Baker" <jdbaker%mylinuxisp.com@localhost>]

Not long before the kernel version bump to 6.99.10, some changes to
powerpc architectures result in kernel panic during boot on macppc
(at least).  First observed in a 6.99.9 kenrel built sometime on
Saturday, 21 July 2012 (previous kernel built Friday, 20 July worked).
Observed on PowerBook G4 and Rev. A iMac.

From iMac (kernel has DEBUG and DIAGNOSIC enabled):
[...]
ohci0 at pci0 dev 20 function 0: Opti 82C861 (rev. 0x10)
csr: 02800016
genppc_pci_intr_map: pin: 1, line: 28
ohci0: interrupting at irq 28
ohci0: OHCI version 1.0, legacy support
usb0 at ohci0: USB revision 1.0
biomask 1f800000 netmask 1f800000 ttymask 1f800000
trap: kernel ISI by 0xc2e37c00 (SRR1 0x40001032), lr: 0x339a14
panic: trap
Stopped in pid 0.1 (system) at  netbsd:cpu_Debugger+0x10:        lwz     
r0,0x14(r1)
0x0098dbb0: at vpanic+0x21c
0x0098dbe0: at panic+0x4c
0x0098dc20: at trap+0x100
0x0098dcb0: kernel ISI trap by 0xc23e7c00: srr1=0x40001032
            r1=0x98dd80 cr=0x20009032 xer=0 ctr=0xc23e7c00
0x0098dd80: at pic_handle_intr+0x198
0x0098ddc0: at trapstart+0x6b0
0x0098de90: at cpu_initclocks+0x40
0x0098dea0: at initclocks+0x44
0x0098deb0: at main+0x258
0x0098df10: at 0x1000a0
db>


Kernels were built from update build, if it makes a difference.

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